In many cases judges use court orders to protect children who are considered vulnerable to extremist behavior. The orders can include making the children wards of court, place them in foster care or prevent them leaving the UK.

President of the Family Division of the High Court Sir James Munby said on Thursday that the number of cases involving children had risen since the beginning of the year.

“Recent months have seen increasing numbers of children cases coming before … the family court,” he said.

“There are allegations that children, with their parents or on their own, are planning or being groomed to travel to parts of Syria controlled by the so-called Islamic State; that children are at risk of being radicalized; or that children are at risk of being involved in terrorist activities either in this country or abroad.”

Munby said police should be proactive in seeking court orders, and not rely on local councils. He added that the safety of vulnerable children was “paramount.”

His announcement came days after Prime Minister David Cameron highlighted the “danger” Islamic extremism poses in the UK, saying the “passive tolerance” of radical ideas was allowing the spread of dangerous rhetoric.

Hannah Stuart, counter-radicalization expert at the Henry Jackson Society, said terror groups are continuing to target young people.

“Both among those who support people joining the conflict in Syria or who want to see terror acts committed here, we see a recurring obsession with the radicalization of children.

“We are seeing a generation who are getting older and having children, and those children are growing up in an environment where there is a risk of them being taken to Syria – or being told that it is right to hate non-Muslims and desire martyrdom.”